This invention relates to a dielectric forming material and a dielectric forming paste, each of which is for use as a transparent dielectric layer formed onto an inside surface of a front glass substrate in a plasma display panel.
An AC type plasma display panel (which may also be referred to as "PDP" hereunder) to which this invention is applicable comprises a front glass substrate for displaying a video image and a rear glass substrate opposed to the front glass substrate with a predetermined gap.
On one hand, the front glass substrate has a plurality of display electrodes and a transparent dielectric layer formed on its inside surface facing the rear glass substrate. The display electrodes are buried in the transparent dielectric layer. An MgO film is formed on a surface of the transparent dielectric layer. On the other hand, the rear glass substrate has a plurality of address electrodes formed on its inside surface facing the front glass substrate.
Between the MgO film on the front glass substrate and the inside surface of the rear glass substrate, a plurality of barrier ribs vertically protrude from the rear glass substrate to be erected thereon to define a plurality of inner spaces between adjacent ones of the barrier ribs. Each of the barrier ribs has a surface covered with a phosphor. An inner space or cavity surrounded by the front and the rear glass substrates is filled with a rare gas. As the glass substrate, use is generally made of a soda lime glass or a high-strain-point glass which has a strain point of 570.degree. C. or more.
With this structure, when an electric voltage is applied to drive the PDP, electric discharge occurs between a selected one of the display electrodes and a selected one of the address electrodes so that ultraviolet rays are emitted from the rare gas. The ultraviolet rays excite the phosphor to emit visible light. The wavelength range of visible light is 620 nm for red, 550 nm for green, and 460 nm for blue.
The light emitted from the phosphor is transmitted through the front glass substrate and the transparent dielectric layer formed thereon. However, a part of the light is scattered on the inside surfaces of the front glass substrate and the transparent dielectric layer and repeatedly reflected on the inside and the outside surfaces thereof. In this event, the light undesiredly leaks into adjacent spaces beyond the barrier ribs. This results in a phenomenon that the video image becomes unclear because of occurrence of glow around a shining point or bright spot. Such phenomenon is generally called a halation.